Pop safety-valve.



No. 630,826. Patented Aug. 8, i899.

B. J. DOWNS.

I P0P SAFETY VALVE. (No (Applmahon filed Dec. 20, 1897. Renewegi Feb. 2;1899.)

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UNITED STATES PATENT OFFICE.

BENJAMIN .I. DOWNS, OF ASHBURNHAM, MASSACHUSETTS, ASSIGNOR OF ONE-THIRDTO HENRY WASIIBURN SMITH DOWNS, OF FITCHBURG,

MASSACHUSETTS.

PO P SAFETY-VALVE.

SPECIFICATION forming part of Letters Patent No. 630,826, dated August8, 1899.

Application filed December 20, 1897- Renewed February 2, 1899. SerialNo. 704,303. (No model.)

To all whmn it may concern:

Be it known that I, BENJAMIN J. Downs, of Ashburnham, in the county ofWorcester and State of Massachusetts, have invented a new and usefulImprovement in Pop Safety- Valves, of which the following, taken inconnection with the accompanying drawings, is a specification.

This invention is in the nature of an im-v provement upon a well-knownclass of safety valves used on locomotives and elsewhere under a highpressure of steam, the object being to prevent the chattering orrumbling sound and the wear upon the parts incident to the trembling ofthe valve as the steam escapes from such pressure.

It is common in pop-valves to press the valve down upon its seat by apowerful spring with an adjusting-screw to give the desired tension, toform an annular recess in the under face of a radial flange on the valveoverhanging its seat, and to apply around said seat athreaded adjustablering having an annular upturned rib adapted to slightly enter saidannular recess, causing the steam thus to pass through an annularchamber immediately surrounding the valve-seat. The conflictingpressures of the spring and the escaping steam make the valve trembleand strike violently upon its seat and inclosing neck, while the outerwall of its recessed flange strikes the rib of the adjustable ring,causing serious wear and the objectionable rumble familiar when alocomotive-engine is delayed at a station. I obviate this in a verysimple way. I have discovered and demonstrated that if an additionalannular chamber is formed in and between said flange andring,surrounding and of greater area than the first, the rate ofvibration is changed by using the steam therein expansively and thenoise ceases.

My invention there fore consists in a safety valve of otherwise suitableconstruction having an adjustable ring surrounding its valveseat andprovided with a spring-pressed valve having a radial flange overhangingsaid ring and a plurality of annular steam-chambers between them.

In the drawings, Figure l is a vertical section of a pop-valve embodyingmy invention, some details of ordinary construction being omitted. Fig.2 is a bottom plan of the movable valve.

A represents the shell or body of the valve, and B the threaded neck onwhich it is mounted.

O is the valve-seat, upon which the valve is pressed by the spring D andadjusting or tension screw E.

F represents the threaded adjustable ring, screwed upon the neck 13,surrounding the valve-seat. Its periphery is milled coarsely or toothed,so that it may be raised or lowered slightly by a partial rotationeiit'ected by introducing a suitable pointed tool through the hole shownoccupied by the small screw G. This ring has,'as heretofore, the annularrib f, beveled or curved upwardly, immediately adjoining the valve-seat.

H is the movable valve,resting by its tapering face upon the valve-seat,its stem having radiating ribs fitting within the neck B and its bodyformed with a marginal flange overhanging the ring F. In the under sideof this flange I form a plurality of annular recesses formingsteam-chambers, two or more, surrounding the valve-seat. The innermostchamber h is such as has heretofore been known, the other, H,of greaterarea, is added by my improvement and receives the steam after its escapeto and action in chamber h. This outermost chamber 11 may be formed ofequal recesses in the ring F and the marginal flange or mainly in theflange only. The construction shown in Fig.1 is highly satisfactory .inpractice.

Steam under full pressure lifts the valve slightly from its seat andescapes first into the chamber h and afterward and immediately into thelarger chamber H, where it expands and its tension is somewhat lessened.Thence it passes between the outer margins of the ring F and valve Hinto the open interior of the body A. The variations in diameter of thevalve at the line of its seat and its outer margin, with the changes inpressure thereat, cause conflicting vibrations which counteract ornullify each other, so that the rumbling sound is suppressed.

I claim as my invention- A safety-valve having an adjustable ringsurrounding its valve-seat, and provided with a spring-pressed valvehaving a radial flange two subscribing witnesses, on this 2d day ofoverhanging said ring, and a plurality ofan- December, A. D. 1897. nularsteam-chambers between them, the

outer chamber having a greater area than the BENJ' DOWNS 5 inner one,substantially asset forth. Vitnesses:

In testimony whereof I have signed my A. H. SPENCER, name to thisspecification, in the presence of H. 0. ROGERS.

